This invention relates generally to gas turbine engines, and more particularly, to methods and apparatus for operating gas turbine engines.
Gas turbine engines typically include an inlet, a fan, low and high pressure compressors, a combustor, and at least one turbine. The compressors compress air which is channeled to the combustor where it is mixed with fuel. The mixture is then ignited for generating hot combustion gases. The combustion gases are channeled to the turbine(s) which extracts energy from the combustion gases for powering the compressor(s), as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator.
During engine operation, significant heat is produced which raises the temperature of engine systems to unacceptable levels. These systems must be cooled to improve their life and reliability. One example is the lubrication system that is utilized to facilitate lubricating components within the gas turbine engine. The lubrication system is configured to channel lubrication fluid to various bearing assemblies within the gas turbine engine. During operation, heat is transmitted to the lubrication fluid from two sources: from heat generated by sliding and rolling friction by components like bearings and seals within a sump and from heat-conduction through the sump wall due to hot air surrounding the sump enclosure.
To facilitate reducing the operational temperature of the lubrication fluid, at least one known gas turbine engine utilizes a conventional radiator that is disposed in the air stream channeled through the engine allowing air that passes through it to cool the fluid circulating within. However, this method has a significant drawback because it presents an obstacle to the smooth airflow, causing both turbulence and pressure drops, which adversely affect engine performance.